The invention relates to a method of and to an apparatus for applying one or more layers of coating material to a substrate, such as a strip or web of textile material, paper (e.g., crepe paper), metallic foil or plastic foil (e.g., a foil of thermoplastic material). More particularly, the invention relates to improvements in methods and apparatus of the type wherein one or more layers of coating material (such as adhesive layers, coloring matter, impregnating substances and the like) are transferred to a substrate, especially to a continuously running substrate, by means of one or more web-like carriers.
It is often necessary and/or desirable to avoid direct application of coating materials to a running substrate (e.g., a substrate which, together with the layer or layers of coating material, is to constitute an adhesive tape, a band aid or the like). For example, if the coating material contains an evaporable solvent which is to be recovered for reuse or to avoid contamination of the surrounding area, the coating material is first applied to one or more web-like carriers and the solvent is expelled from the individual layer or layers on the carrier or carriers prior to transfer of the desolventized layer or layers onto the substrate. It is also known to heat the layer or layers on the respective carrier(s) to promote the evaporation of solvent prior to transfer of the layer or layers onto the substrate. As a rule, the solvent is recovered by contacting the layer or layers with an inert gas, such as nitrogen.